| Message ID | 20180109143339.GC4356@ming.t460p (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09.01.2018 17:33, Ming Lei wrote: > On Tue, Jan 09, 2018 at 04:18:39PM +0300, Dmitry Osipenko wrote: >> On 09.01.2018 05:34, Ming Lei wrote: >>> On Tue, Jan 09, 2018 at 12:09:27AM +0300, Dmitry Osipenko wrote: >>>> On 18.12.2017 15:22, Ming Lei wrote: >>>>> When merging one bvec into segment, if the bvec is too big >>>>> to merge, current policy is to move the whole bvec into another >>>>> new segment. >>>>> >>>>> This patchset changes the policy into trying to maximize size of >>>>> front segments, that means in above situation, part of bvec >>>>> is merged into current segment, and the remainder is put >>>>> into next segment. >>>>> >>>>> This patch prepares for support multipage bvec because >>>>> it can be quite common to see this case and we should try >>>>> to make front segments in full size. >>>>> >>>>> Signed-off-by: Ming Lei <ming.lei@redhat.com> >>>>> --- >>>>> block/blk-merge.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++----- >>>>> 1 file changed, 49 insertions(+), 5 deletions(-) >>>>> >>>>> diff --git a/block/blk-merge.c b/block/blk-merge.c >>>>> index a476337a8ff4..42ceb89bc566 100644 >>>>> --- a/block/blk-merge.c >>>>> +++ b/block/blk-merge.c >>>>> @@ -109,6 +109,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, >>>>> bool do_split = true; >>>>> struct bio *new = NULL; >>>>> const unsigned max_sectors = get_max_io_size(q, bio); >>>>> + unsigned advance = 0; >>>>> >>>>> bio_for_each_segment(bv, bio, iter) { >>>>> /* >>>>> @@ -134,12 +135,32 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, >>>>> } >>>>> >>>>> if (bvprvp && blk_queue_cluster(q)) { >>>>> - if (seg_size + bv.bv_len > queue_max_segment_size(q)) >>>>> - goto new_segment; >>>>> if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) >>>>> goto new_segment; >>>>> if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) >>>>> goto new_segment; >>>>> + if (seg_size + bv.bv_len > queue_max_segment_size(q)) { >>>>> + /* >>>>> + * On assumption is that initial value of >>>>> + * @seg_size(equals to bv.bv_len) won't be >>>>> + * bigger than max segment size, but will >>>>> + * becomes false after multipage bvec comes. >>>>> + */ >>>>> + advance = queue_max_segment_size(q) - seg_size; >>>>> + >>>>> + if (advance > 0) { >>>>> + seg_size += advance; >>>>> + sectors += advance >> 9; >>>>> + bv.bv_len -= advance; >>>>> + bv.bv_offset += advance; >>>>> + } >>>>> + >>>>> + /* >>>>> + * Still need to put remainder of current >>>>> + * bvec into a new segment. >>>>> + */ >>>>> + goto new_segment; >>>>> + } >>>>> >>>>> seg_size += bv.bv_len; >>>>> bvprv = bv; >>>>> @@ -161,6 +182,12 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, >>>>> seg_size = bv.bv_len; >>>>> sectors += bv.bv_len >> 9; >>>>> >>>>> + /* restore the bvec for iterator */ >>>>> + if (advance) { >>>>> + bv.bv_len += advance; >>>>> + bv.bv_offset -= advance; >>>>> + advance = 0; >>>>> + } >>>>> } >>>>> >>>>> do_split = false; >>>>> @@ -361,16 +388,29 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, >>>>> { >>>>> >>>>> int nbytes = bvec->bv_len; >>>>> + unsigned advance = 0; >>>>> >>>>> if (*sg && *cluster) { >>>>> - if ((*sg)->length + nbytes > queue_max_segment_size(q)) >>>>> - goto new_segment; >>>>> - >>>>> if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) >>>>> goto new_segment; >>>>> if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) >>>>> goto new_segment; >>>>> >>>>> + /* >>>>> + * try best to merge part of the bvec into previous >>>>> + * segment and follow same policy with >>>>> + * blk_bio_segment_split() >>>>> + */ >>>>> + if ((*sg)->length + nbytes > queue_max_segment_size(q)) { >>>>> + advance = queue_max_segment_size(q) - (*sg)->length; >>>>> + if (advance) { >>>>> + (*sg)->length += advance; >>>>> + bvec->bv_offset += advance; >>>>> + bvec->bv_len -= advance; >>>>> + } >>>>> + goto new_segment; >>>>> + } >>>>> + >>>>> (*sg)->length += nbytes; >>>>> } else { >>>>> new_segment: >>>>> @@ -393,6 +433,10 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, >>>>> >>>>> sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); >>>>> (*nsegs)++; >>>>> + >>>>> + /* for making iterator happy */ >>>>> + bvec->bv_offset -= advance; >>>>> + bvec->bv_len += advance; >>>>> } >>>>> *bvprv = *bvec; >>>>> } >>>>> >>>> >>>> Hello, >>>> >>>> This patch breaks MMC on next-20180108, in particular MMC doesn't work anymore >>>> with this patch on NVIDIA Tegra20: >>>> >>>> <3>[ 36.622253] print_req_error: I/O error, dev mmcblk1, sector 512 >>>> <3>[ 36.671233] print_req_error: I/O error, dev mmcblk2, sector 128 >>>> <3>[ 36.711308] print_req_error: I/O error, dev mmcblk1, sector 31325304 >>>> <3>[ 36.749232] print_req_error: I/O error, dev mmcblk2, sector 512 >>>> <3>[ 36.761235] print_req_error: I/O error, dev mmcblk1, sector 31325816 >>>> <3>[ 36.832039] print_req_error: I/O error, dev mmcblk2, sector 31259768 >>>> <3>[ 99.793248] print_req_error: I/O error, dev mmcblk1, sector 31323136 >>>> <3>[ 99.982043] print_req_error: I/O error, dev mmcblk1, sector 929792 >>>> <3>[ 99.986301] print_req_error: I/O error, dev mmcblk1, sector 930816 >>>> <3>[ 100.293624] print_req_error: I/O error, dev mmcblk1, sector 932864 >>>> <3>[ 100.466839] print_req_error: I/O error, dev mmcblk1, sector 947200 >>>> <3>[ 100.642955] print_req_error: I/O error, dev mmcblk1, sector 949248 >>>> <3>[ 100.818838] print_req_error: I/O error, dev mmcblk1, sector 230400 >>>> >>>> Any attempt of mounting MMC block dev ends with a kernel crash. Reverting this >>>> patch fixes the issue. >>> >>> Hi Dmitry, >>> >>> Thanks for your report! >>> >>> Could you share us what the segment limits are on your MMC? >>> >>> cat /sys/block/mmcN/queue/max_segment_size >>> cat /sys/block/mmcN/queue/max_segments >>> >>> Please test the following patch to see if your issue can be fixed? >>> >>> --- >>> diff --git a/block/blk-merge.c b/block/blk-merge.c >>> index 446f63e076aa..cfab36c26608 100644 >>> --- a/block/blk-merge.c >>> +++ b/block/blk-merge.c >>> @@ -431,12 +431,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, >>> >>> sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); >>> (*nsegs)++; >>> + } >>> >>> + *bvprv = *bvec; >>> + if (advance) { >>> /* for making iterator happy */ >>> bvec->bv_offset -= advance; >>> bvec->bv_len += advance; >>> } >>> - *bvprv = *bvec; >>> } >>> >>> static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, >> >> Hi Ming, >> >> I've tried your patch and unfortunately it doesn't help with the issue. >> >> Here are the segment limits: >> >> # cat /sys/block/mmc*/queue/max_segment_size >> 65535 > > Hi Dmitry, > > The 'max_segment_size' of 65535 should be the reason, could you test the > following patch? > > --- > diff --git a/block/blk-merge.c b/block/blk-merge.c > index 446f63e076aa..38a66e3e678e 100644 > --- a/block/blk-merge.c > +++ b/block/blk-merge.c > @@ -12,6 +12,8 @@ > > #include "blk.h" > > +#define sector_align(x) ALIGN_DOWN(x, 512) > + > static struct bio *blk_bio_discard_split(struct request_queue *q, > struct bio *bio, > struct bio_set *bs, > @@ -109,7 +111,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > bool do_split = true; > struct bio *new = NULL; > const unsigned max_sectors = get_max_io_size(q, bio); > - unsigned advance = 0; > + int advance = 0; > > bio_for_each_segment(bv, bio, iter) { > /* > @@ -144,8 +146,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > * bigger than max segment size, but this > * becomes false after multipage bvecs. > */ > - advance = queue_max_segment_size(q) - seg_size; > - > + advance = sector_align( > + queue_max_segment_size(q) - > + seg_size); > if (advance > 0) { > seg_size += advance; > sectors += advance >> 9; > @@ -386,7 +389,7 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > { > > int nbytes = bvec->bv_len; > - unsigned advance = 0; > + int advance = 0; > > if (*sg && *cluster) { > if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) > @@ -400,8 +403,9 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > * blk_bio_segment_split() > */ > if ((*sg)->length + nbytes > queue_max_segment_size(q)) { > - advance = queue_max_segment_size(q) - (*sg)->length; > - if (advance) { > + advance = sector_align(queue_max_segment_size(q) - > + (*sg)->length); > + if (advance > 0) { > (*sg)->length += advance; > bvec->bv_offset += advance; > bvec->bv_len -= advance; > @@ -431,12 +435,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > > sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); > (*nsegs)++; > + } > > + *bvprv = *bvec; > + if (advance > 0) { > /* for making iterator happy */ > bvec->bv_offset -= advance; > bvec->bv_len += advance; > } > - *bvprv = *bvec; > } > > static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, This patch doesn't help either.
On Tue, Jan 09, 2018 at 08:02:53PM +0300, Dmitry Osipenko wrote: > On 09.01.2018 17:33, Ming Lei wrote: > > On Tue, Jan 09, 2018 at 04:18:39PM +0300, Dmitry Osipenko wrote: > >> On 09.01.2018 05:34, Ming Lei wrote: > >>> On Tue, Jan 09, 2018 at 12:09:27AM +0300, Dmitry Osipenko wrote: > >>>> On 18.12.2017 15:22, Ming Lei wrote: > >>>>> When merging one bvec into segment, if the bvec is too big > >>>>> to merge, current policy is to move the whole bvec into another > >>>>> new segment. > >>>>> > >>>>> This patchset changes the policy into trying to maximize size of > >>>>> front segments, that means in above situation, part of bvec > >>>>> is merged into current segment, and the remainder is put > >>>>> into next segment. > >>>>> > >>>>> This patch prepares for support multipage bvec because > >>>>> it can be quite common to see this case and we should try > >>>>> to make front segments in full size. > >>>>> > >>>>> Signed-off-by: Ming Lei <ming.lei@redhat.com> > >>>>> --- > >>>>> block/blk-merge.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++----- > >>>>> 1 file changed, 49 insertions(+), 5 deletions(-) > >>>>> > >>>>> diff --git a/block/blk-merge.c b/block/blk-merge.c > >>>>> index a476337a8ff4..42ceb89bc566 100644 > >>>>> --- a/block/blk-merge.c > >>>>> +++ b/block/blk-merge.c > >>>>> @@ -109,6 +109,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > >>>>> bool do_split = true; > >>>>> struct bio *new = NULL; > >>>>> const unsigned max_sectors = get_max_io_size(q, bio); > >>>>> + unsigned advance = 0; > >>>>> > >>>>> bio_for_each_segment(bv, bio, iter) { > >>>>> /* > >>>>> @@ -134,12 +135,32 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > >>>>> } > >>>>> > >>>>> if (bvprvp && blk_queue_cluster(q)) { > >>>>> - if (seg_size + bv.bv_len > queue_max_segment_size(q)) > >>>>> - goto new_segment; > >>>>> if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) > >>>>> goto new_segment; > >>>>> if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) > >>>>> goto new_segment; > >>>>> + if (seg_size + bv.bv_len > queue_max_segment_size(q)) { > >>>>> + /* > >>>>> + * On assumption is that initial value of > >>>>> + * @seg_size(equals to bv.bv_len) won't be > >>>>> + * bigger than max segment size, but will > >>>>> + * becomes false after multipage bvec comes. > >>>>> + */ > >>>>> + advance = queue_max_segment_size(q) - seg_size; > >>>>> + > >>>>> + if (advance > 0) { > >>>>> + seg_size += advance; > >>>>> + sectors += advance >> 9; > >>>>> + bv.bv_len -= advance; > >>>>> + bv.bv_offset += advance; > >>>>> + } > >>>>> + > >>>>> + /* > >>>>> + * Still need to put remainder of current > >>>>> + * bvec into a new segment. > >>>>> + */ > >>>>> + goto new_segment; > >>>>> + } > >>>>> > >>>>> seg_size += bv.bv_len; > >>>>> bvprv = bv; > >>>>> @@ -161,6 +182,12 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > >>>>> seg_size = bv.bv_len; > >>>>> sectors += bv.bv_len >> 9; > >>>>> > >>>>> + /* restore the bvec for iterator */ > >>>>> + if (advance) { > >>>>> + bv.bv_len += advance; > >>>>> + bv.bv_offset -= advance; > >>>>> + advance = 0; > >>>>> + } > >>>>> } > >>>>> > >>>>> do_split = false; > >>>>> @@ -361,16 +388,29 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > >>>>> { > >>>>> > >>>>> int nbytes = bvec->bv_len; > >>>>> + unsigned advance = 0; > >>>>> > >>>>> if (*sg && *cluster) { > >>>>> - if ((*sg)->length + nbytes > queue_max_segment_size(q)) > >>>>> - goto new_segment; > >>>>> - > >>>>> if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) > >>>>> goto new_segment; > >>>>> if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) > >>>>> goto new_segment; > >>>>> > >>>>> + /* > >>>>> + * try best to merge part of the bvec into previous > >>>>> + * segment and follow same policy with > >>>>> + * blk_bio_segment_split() > >>>>> + */ > >>>>> + if ((*sg)->length + nbytes > queue_max_segment_size(q)) { > >>>>> + advance = queue_max_segment_size(q) - (*sg)->length; > >>>>> + if (advance) { > >>>>> + (*sg)->length += advance; > >>>>> + bvec->bv_offset += advance; > >>>>> + bvec->bv_len -= advance; > >>>>> + } > >>>>> + goto new_segment; > >>>>> + } > >>>>> + > >>>>> (*sg)->length += nbytes; > >>>>> } else { > >>>>> new_segment: > >>>>> @@ -393,6 +433,10 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > >>>>> > >>>>> sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); > >>>>> (*nsegs)++; > >>>>> + > >>>>> + /* for making iterator happy */ > >>>>> + bvec->bv_offset -= advance; > >>>>> + bvec->bv_len += advance; > >>>>> } > >>>>> *bvprv = *bvec; > >>>>> } > >>>>> > >>>> > >>>> Hello, > >>>> > >>>> This patch breaks MMC on next-20180108, in particular MMC doesn't work anymore > >>>> with this patch on NVIDIA Tegra20: > >>>> > >>>> <3>[ 36.622253] print_req_error: I/O error, dev mmcblk1, sector 512 > >>>> <3>[ 36.671233] print_req_error: I/O error, dev mmcblk2, sector 128 > >>>> <3>[ 36.711308] print_req_error: I/O error, dev mmcblk1, sector 31325304 > >>>> <3>[ 36.749232] print_req_error: I/O error, dev mmcblk2, sector 512 > >>>> <3>[ 36.761235] print_req_error: I/O error, dev mmcblk1, sector 31325816 > >>>> <3>[ 36.832039] print_req_error: I/O error, dev mmcblk2, sector 31259768 > >>>> <3>[ 99.793248] print_req_error: I/O error, dev mmcblk1, sector 31323136 > >>>> <3>[ 99.982043] print_req_error: I/O error, dev mmcblk1, sector 929792 > >>>> <3>[ 99.986301] print_req_error: I/O error, dev mmcblk1, sector 930816 > >>>> <3>[ 100.293624] print_req_error: I/O error, dev mmcblk1, sector 932864 > >>>> <3>[ 100.466839] print_req_error: I/O error, dev mmcblk1, sector 947200 > >>>> <3>[ 100.642955] print_req_error: I/O error, dev mmcblk1, sector 949248 > >>>> <3>[ 100.818838] print_req_error: I/O error, dev mmcblk1, sector 230400 > >>>> > >>>> Any attempt of mounting MMC block dev ends with a kernel crash. Reverting this > >>>> patch fixes the issue. > >>> > >>> Hi Dmitry, > >>> > >>> Thanks for your report! > >>> > >>> Could you share us what the segment limits are on your MMC? > >>> > >>> cat /sys/block/mmcN/queue/max_segment_size > >>> cat /sys/block/mmcN/queue/max_segments > >>> > >>> Please test the following patch to see if your issue can be fixed? > >>> > >>> --- > >>> diff --git a/block/blk-merge.c b/block/blk-merge.c > >>> index 446f63e076aa..cfab36c26608 100644 > >>> --- a/block/blk-merge.c > >>> +++ b/block/blk-merge.c > >>> @@ -431,12 +431,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > >>> > >>> sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); > >>> (*nsegs)++; > >>> + } > >>> > >>> + *bvprv = *bvec; > >>> + if (advance) { > >>> /* for making iterator happy */ > >>> bvec->bv_offset -= advance; > >>> bvec->bv_len += advance; > >>> } > >>> - *bvprv = *bvec; > >>> } > >>> > >>> static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, > >> > >> Hi Ming, > >> > >> I've tried your patch and unfortunately it doesn't help with the issue. > >> > >> Here are the segment limits: > >> > >> # cat /sys/block/mmc*/queue/max_segment_size > >> 65535 > > > > Hi Dmitry, > > > > The 'max_segment_size' of 65535 should be the reason, could you test the > > following patch? > > > > --- > > diff --git a/block/blk-merge.c b/block/blk-merge.c > > index 446f63e076aa..38a66e3e678e 100644 > > --- a/block/blk-merge.c > > +++ b/block/blk-merge.c > > @@ -12,6 +12,8 @@ > > > > #include "blk.h" > > > > +#define sector_align(x) ALIGN_DOWN(x, 512) > > + > > static struct bio *blk_bio_discard_split(struct request_queue *q, > > struct bio *bio, > > struct bio_set *bs, > > @@ -109,7 +111,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > > bool do_split = true; > > struct bio *new = NULL; > > const unsigned max_sectors = get_max_io_size(q, bio); > > - unsigned advance = 0; > > + int advance = 0; > > > > bio_for_each_segment(bv, bio, iter) { > > /* > > @@ -144,8 +146,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > > * bigger than max segment size, but this > > * becomes false after multipage bvecs. > > */ > > - advance = queue_max_segment_size(q) - seg_size; > > - > > + advance = sector_align( > > + queue_max_segment_size(q) - > > + seg_size); > > if (advance > 0) { > > seg_size += advance; > > sectors += advance >> 9; > > @@ -386,7 +389,7 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > > { > > > > int nbytes = bvec->bv_len; > > - unsigned advance = 0; > > + int advance = 0; > > > > if (*sg && *cluster) { > > if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) > > @@ -400,8 +403,9 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > > * blk_bio_segment_split() > > */ > > if ((*sg)->length + nbytes > queue_max_segment_size(q)) { > > - advance = queue_max_segment_size(q) - (*sg)->length; > > - if (advance) { > > + advance = sector_align(queue_max_segment_size(q) - > > + (*sg)->length); > > + if (advance > 0) { > > (*sg)->length += advance; > > bvec->bv_offset += advance; > > bvec->bv_len -= advance; > > @@ -431,12 +435,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > > > > sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); > > (*nsegs)++; > > + } > > > > + *bvprv = *bvec; > > + if (advance > 0) { > > /* for making iterator happy */ > > bvec->bv_offset -= advance; > > bvec->bv_len += advance; > > } > > - *bvprv = *bvec; > > } > > > > static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, > > This patch doesn't help either. OK, I will send a revert later. Thinking of the patch further, we don't need this kind of logic for multipage bvec at all since almost all bvecs won't be contiguous if bio_add_page() is used after multipage bvec is enabled. Thanks, Ming
On 10.01.2018 05:40, Ming Lei wrote: > On Tue, Jan 09, 2018 at 08:02:53PM +0300, Dmitry Osipenko wrote: >> On 09.01.2018 17:33, Ming Lei wrote: >>> On Tue, Jan 09, 2018 at 04:18:39PM +0300, Dmitry Osipenko wrote: >>>> On 09.01.2018 05:34, Ming Lei wrote: >>>>> On Tue, Jan 09, 2018 at 12:09:27AM +0300, Dmitry Osipenko wrote: >>>>>> On 18.12.2017 15:22, Ming Lei wrote: >>>>>>> When merging one bvec into segment, if the bvec is too big >>>>>>> to merge, current policy is to move the whole bvec into another >>>>>>> new segment. >>>>>>> >>>>>>> This patchset changes the policy into trying to maximize size of >>>>>>> front segments, that means in above situation, part of bvec >>>>>>> is merged into current segment, and the remainder is put >>>>>>> into next segment. >>>>>>> >>>>>>> This patch prepares for support multipage bvec because >>>>>>> it can be quite common to see this case and we should try >>>>>>> to make front segments in full size. >>>>>>> >>>>>>> Signed-off-by: Ming Lei <ming.lei@redhat.com> >>>>>>> --- >>>>>>> block/blk-merge.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++----- >>>>>>> 1 file changed, 49 insertions(+), 5 deletions(-) >>>>>>> >>>>>>> diff --git a/block/blk-merge.c b/block/blk-merge.c >>>>>>> index a476337a8ff4..42ceb89bc566 100644 >>>>>>> --- a/block/blk-merge.c >>>>>>> +++ b/block/blk-merge.c >>>>>>> @@ -109,6 +109,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, >>>>>>> bool do_split = true; >>>>>>> struct bio *new = NULL; >>>>>>> const unsigned max_sectors = get_max_io_size(q, bio); >>>>>>> + unsigned advance = 0; >>>>>>> >>>>>>> bio_for_each_segment(bv, bio, iter) { >>>>>>> /* >>>>>>> @@ -134,12 +135,32 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, >>>>>>> } >>>>>>> >>>>>>> if (bvprvp && blk_queue_cluster(q)) { >>>>>>> - if (seg_size + bv.bv_len > queue_max_segment_size(q)) >>>>>>> - goto new_segment; >>>>>>> if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) >>>>>>> goto new_segment; >>>>>>> if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) >>>>>>> goto new_segment; >>>>>>> + if (seg_size + bv.bv_len > queue_max_segment_size(q)) { >>>>>>> + /* >>>>>>> + * On assumption is that initial value of >>>>>>> + * @seg_size(equals to bv.bv_len) won't be >>>>>>> + * bigger than max segment size, but will >>>>>>> + * becomes false after multipage bvec comes. >>>>>>> + */ >>>>>>> + advance = queue_max_segment_size(q) - seg_size; >>>>>>> + >>>>>>> + if (advance > 0) { >>>>>>> + seg_size += advance; >>>>>>> + sectors += advance >> 9; >>>>>>> + bv.bv_len -= advance; >>>>>>> + bv.bv_offset += advance; >>>>>>> + } >>>>>>> + >>>>>>> + /* >>>>>>> + * Still need to put remainder of current >>>>>>> + * bvec into a new segment. >>>>>>> + */ >>>>>>> + goto new_segment; >>>>>>> + } >>>>>>> >>>>>>> seg_size += bv.bv_len; >>>>>>> bvprv = bv; >>>>>>> @@ -161,6 +182,12 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, >>>>>>> seg_size = bv.bv_len; >>>>>>> sectors += bv.bv_len >> 9; >>>>>>> >>>>>>> + /* restore the bvec for iterator */ >>>>>>> + if (advance) { >>>>>>> + bv.bv_len += advance; >>>>>>> + bv.bv_offset -= advance; >>>>>>> + advance = 0; >>>>>>> + } >>>>>>> } >>>>>>> >>>>>>> do_split = false; >>>>>>> @@ -361,16 +388,29 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, >>>>>>> { >>>>>>> >>>>>>> int nbytes = bvec->bv_len; >>>>>>> + unsigned advance = 0; >>>>>>> >>>>>>> if (*sg && *cluster) { >>>>>>> - if ((*sg)->length + nbytes > queue_max_segment_size(q)) >>>>>>> - goto new_segment; >>>>>>> - >>>>>>> if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) >>>>>>> goto new_segment; >>>>>>> if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) >>>>>>> goto new_segment; >>>>>>> >>>>>>> + /* >>>>>>> + * try best to merge part of the bvec into previous >>>>>>> + * segment and follow same policy with >>>>>>> + * blk_bio_segment_split() >>>>>>> + */ >>>>>>> + if ((*sg)->length + nbytes > queue_max_segment_size(q)) { >>>>>>> + advance = queue_max_segment_size(q) - (*sg)->length; >>>>>>> + if (advance) { >>>>>>> + (*sg)->length += advance; >>>>>>> + bvec->bv_offset += advance; >>>>>>> + bvec->bv_len -= advance; >>>>>>> + } >>>>>>> + goto new_segment; >>>>>>> + } >>>>>>> + >>>>>>> (*sg)->length += nbytes; >>>>>>> } else { >>>>>>> new_segment: >>>>>>> @@ -393,6 +433,10 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, >>>>>>> >>>>>>> sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); >>>>>>> (*nsegs)++; >>>>>>> + >>>>>>> + /* for making iterator happy */ >>>>>>> + bvec->bv_offset -= advance; >>>>>>> + bvec->bv_len += advance; >>>>>>> } >>>>>>> *bvprv = *bvec; >>>>>>> } >>>>>>> >>>>>> >>>>>> Hello, >>>>>> >>>>>> This patch breaks MMC on next-20180108, in particular MMC doesn't work anymore >>>>>> with this patch on NVIDIA Tegra20: >>>>>> >>>>>> <3>[ 36.622253] print_req_error: I/O error, dev mmcblk1, sector 512 >>>>>> <3>[ 36.671233] print_req_error: I/O error, dev mmcblk2, sector 128 >>>>>> <3>[ 36.711308] print_req_error: I/O error, dev mmcblk1, sector 31325304 >>>>>> <3>[ 36.749232] print_req_error: I/O error, dev mmcblk2, sector 512 >>>>>> <3>[ 36.761235] print_req_error: I/O error, dev mmcblk1, sector 31325816 >>>>>> <3>[ 36.832039] print_req_error: I/O error, dev mmcblk2, sector 31259768 >>>>>> <3>[ 99.793248] print_req_error: I/O error, dev mmcblk1, sector 31323136 >>>>>> <3>[ 99.982043] print_req_error: I/O error, dev mmcblk1, sector 929792 >>>>>> <3>[ 99.986301] print_req_error: I/O error, dev mmcblk1, sector 930816 >>>>>> <3>[ 100.293624] print_req_error: I/O error, dev mmcblk1, sector 932864 >>>>>> <3>[ 100.466839] print_req_error: I/O error, dev mmcblk1, sector 947200 >>>>>> <3>[ 100.642955] print_req_error: I/O error, dev mmcblk1, sector 949248 >>>>>> <3>[ 100.818838] print_req_error: I/O error, dev mmcblk1, sector 230400 >>>>>> >>>>>> Any attempt of mounting MMC block dev ends with a kernel crash. Reverting this >>>>>> patch fixes the issue. >>>>> >>>>> Hi Dmitry, >>>>> >>>>> Thanks for your report! >>>>> >>>>> Could you share us what the segment limits are on your MMC? >>>>> >>>>> cat /sys/block/mmcN/queue/max_segment_size >>>>> cat /sys/block/mmcN/queue/max_segments >>>>> >>>>> Please test the following patch to see if your issue can be fixed? >>>>> >>>>> --- >>>>> diff --git a/block/blk-merge.c b/block/blk-merge.c >>>>> index 446f63e076aa..cfab36c26608 100644 >>>>> --- a/block/blk-merge.c >>>>> +++ b/block/blk-merge.c >>>>> @@ -431,12 +431,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, >>>>> >>>>> sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); >>>>> (*nsegs)++; >>>>> + } >>>>> >>>>> + *bvprv = *bvec; >>>>> + if (advance) { >>>>> /* for making iterator happy */ >>>>> bvec->bv_offset -= advance; >>>>> bvec->bv_len += advance; >>>>> } >>>>> - *bvprv = *bvec; >>>>> } >>>>> >>>>> static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, >>>> >>>> Hi Ming, >>>> >>>> I've tried your patch and unfortunately it doesn't help with the issue. >>>> >>>> Here are the segment limits: >>>> >>>> # cat /sys/block/mmc*/queue/max_segment_size >>>> 65535 >>> >>> Hi Dmitry, >>> >>> The 'max_segment_size' of 65535 should be the reason, could you test the >>> following patch? >>> >>> --- >>> diff --git a/block/blk-merge.c b/block/blk-merge.c >>> index 446f63e076aa..38a66e3e678e 100644 >>> --- a/block/blk-merge.c >>> +++ b/block/blk-merge.c >>> @@ -12,6 +12,8 @@ >>> >>> #include "blk.h" >>> >>> +#define sector_align(x) ALIGN_DOWN(x, 512) >>> + >>> static struct bio *blk_bio_discard_split(struct request_queue *q, >>> struct bio *bio, >>> struct bio_set *bs, >>> @@ -109,7 +111,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, >>> bool do_split = true; >>> struct bio *new = NULL; >>> const unsigned max_sectors = get_max_io_size(q, bio); >>> - unsigned advance = 0; >>> + int advance = 0; >>> >>> bio_for_each_segment(bv, bio, iter) { >>> /* >>> @@ -144,8 +146,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, >>> * bigger than max segment size, but this >>> * becomes false after multipage bvecs. >>> */ >>> - advance = queue_max_segment_size(q) - seg_size; >>> - >>> + advance = sector_align( >>> + queue_max_segment_size(q) - >>> + seg_size); >>> if (advance > 0) { >>> seg_size += advance; >>> sectors += advance >> 9; >>> @@ -386,7 +389,7 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, >>> { >>> >>> int nbytes = bvec->bv_len; >>> - unsigned advance = 0; >>> + int advance = 0; >>> >>> if (*sg && *cluster) { >>> if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) >>> @@ -400,8 +403,9 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, >>> * blk_bio_segment_split() >>> */ >>> if ((*sg)->length + nbytes > queue_max_segment_size(q)) { >>> - advance = queue_max_segment_size(q) - (*sg)->length; >>> - if (advance) { >>> + advance = sector_align(queue_max_segment_size(q) - >>> + (*sg)->length); >>> + if (advance > 0) { >>> (*sg)->length += advance; >>> bvec->bv_offset += advance; >>> bvec->bv_len -= advance; >>> @@ -431,12 +435,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, >>> >>> sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); >>> (*nsegs)++; >>> + } >>> >>> + *bvprv = *bvec; >>> + if (advance > 0) { >>> /* for making iterator happy */ >>> bvec->bv_offset -= advance; >>> bvec->bv_len += advance; >>> } >>> - *bvprv = *bvec; >>> } >>> >>> static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, >> >> This patch doesn't help either. > > OK, I will send a revert later. > > Thinking of the patch further, we don't need this kind of logic for > multipage bvec at all since almost all bvecs won't be contiguous if > bio_add_page() is used after multipage bvec is enabled. Revert works for me, thanks.
diff --git a/block/blk-merge.c b/block/blk-merge.c index 446f63e076aa..38a66e3e678e 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -12,6 +12,8 @@ #include "blk.h" +#define sector_align(x) ALIGN_DOWN(x, 512) + static struct bio *blk_bio_discard_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, @@ -109,7 +111,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bool do_split = true; struct bio *new = NULL; const unsigned max_sectors = get_max_io_size(q, bio); - unsigned advance = 0; + int advance = 0; bio_for_each_segment(bv, bio, iter) { /* @@ -144,8 +146,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, * bigger than max segment size, but this * becomes false after multipage bvecs. */ - advance = queue_max_segment_size(q) - seg_size; - + advance = sector_align( + queue_max_segment_size(q) - + seg_size); if (advance > 0) { seg_size += advance; sectors += advance >> 9; @@ -386,7 +389,7 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, { int nbytes = bvec->bv_len; - unsigned advance = 0; + int advance = 0; if (*sg && *cluster) { if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) @@ -400,8 +403,9 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, * blk_bio_segment_split() */ if ((*sg)->length + nbytes > queue_max_segment_size(q)) { - advance = queue_max_segment_size(q) - (*sg)->length; - if (advance) { + advance = sector_align(queue_max_segment_size(q) - + (*sg)->length); + if (advance > 0) { (*sg)->length += advance; bvec->bv_offset += advance; bvec->bv_len -= advance; @@ -431,12 +435,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); (*nsegs)++; + } + *bvprv = *bvec; + if (advance > 0) { /* for making iterator happy */ bvec->bv_offset -= advance; bvec->bv_len += advance; } - *bvprv = *bvec; } static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv,